1. Field of the Invention
The present invention relates to a method for manufacturing a liquid ejection head.
2. Description of the Related Art
Liquid ejection apparatuses are known as apparatuses in which a liquid is ejected from an ejection port onto a recording medium to record images. In liquid ejection apparatuses, an ejection port is formed in a liquid ejection head. Such an ejection port is formed by, for example, conducting exposure and development of a photosensitive resin layer disposed on or above a substrate.
In recent years, there has been a demand for recording of high-resolution images, which has lead to a need to decrease the size of liquid droplets to be ejected. The size of liquid droplets to be ejected may be decreased by reducing the diameter of an ejection port; however, simply reducing the diameter of an ejection port increases the fluid resistance of liquid droplets during ejection thereof. A problem such as a decreased ejection rate of liquid droplets therefore occurs in some cases.
An ejection port having a so-called tapered shape is known as an ejection port used for overcoming such a problem, in which the cross-sectional area of the ejection port decreases as it extends from the substrate side toward a surface in which the ejection port opens. In a method disclosed in Japanese Patent No. 4498363, a recess is formed in a surface of a photosensitive resin layer (side that serves as a surface in which the ejection port opens), and a tapered ejection port is formed at the bottom of the recess by photolithography. In this method, the recess functions as a concave lens in an exposure process, and light can be refracted by the concave lens to form an ejection port into a tapered shape.